1. Field of the Invention
The present invention relates generally to printing presses and more particularly to a device and method for trimming printed products.
2. Background Information
Web printing presses print a continuous web of material, such as paper. The continuous web then is cut in a cutting unit so as to form book blocks. These book blocks can be sections of a newspaper, for example. These book blocks typically require further processing, including the trimming of edges, so that uniform and straight edges result. To perform a trimming operation, it is often desirable to slow the product stream. This may be accomplished by splitting the product stream and then to decelerating the resultant split product streams. This often requires a large amount of floor space.
U.S. Pat. No. 3,811,350 discloses a sheet material trimming method and apparatus, in which sheet material is transferred by a conveyor belt to a first trimming station where a face edge of the sheet material is trimmed. The sheet material is then transferred to a second trimming station where the head and trail edges are trimmed. The knife assemblies may be operated by a crank drive.
This device has the disadvantage that only a single stream of products is processed. Moreover, the drives disclosed for the various knives are complicated.
An object of the present invention is to provide for a device and method for trimming printed products in a simplified manner. An additional or alternative object of the present invention is to be able to trim multiple product streams in a coordinated fashion.
The present invention provides a device for trimming multiple streams of printed products including a first trimming unit for trimming at least one side of a first stream of printed products and a second trimming unit for trimming at least one side of a second stream of printed products. The first stream and the second stream having a similar direction. By trimming two separate streams moving in a similar direction, the throughput of the trimmer may be increased.
The device preferably has a common drive unit, the first and second trimming units being connected to and driven by the common drive unit. The common drive unit simplifies timing of the cuts of the trimming units. The common drive unit may include a central drive shaft.
The device may further include a third trimming unit for trimming at least one side of a third stream of printed products and a fourth trimming unit for trimming at least one side of a second stream of printed products. The first stream, the second stream, the third stream and the fourth stream have a similar direction. The common drive unit may then be connected to and drive the first, second, third and fourth trimming units. The first, second, third and fourth trimming units preferably define a circle, with the common drive unit being located centrally in the circle.
The first stream and the second stream preferably move in parallel.
Another trimming unit for trimming at least one further side of the first stream may be provided.
The first trimming unit may include a blade, a blade support, and two rods fixedly connected to the blade support, with the two rods being connected to a drive unit. Ink jet station for the product streams may be provided to add further printing, for example addresses or names, to the printed products.
A common frame may support the first and second trimming units.
The present invention also provides a method for trimming multiple streams of printed products including the steps of moving a first stream of printed products in a first direction, trimming at least one side of the first stream, moving a second stream of printed products separate from the first stream in a direction similar to the first direction, and trimming at least one side of the second stream.
The first stream and the second stream preferably are moved in parallel. The streams also preferably are moved in an indexed manner through the trimmer.